Projectile equipped with fins



Feb. 2l, i950 J. R. .JAssE PROJECTILE EQUIPPED WITH FINS Filed May 24,1947 ns, thev body of Patented Feb. 21, 1950 Joseph RaymondEtablissements French company J asse, Paris, France, assigner to EdgarBrandt, Paris, France, a

Application Mayu, 1947, serial No. 750,253

` In France June 5, 1946 4 Claims. (c1. 1oz-49) The body of a projectilemaybe manufactured in"various ways, and in particular from a forgedfbar, or by moulding (semisteel), which is the `most common method oragain by shrinking a steel tube.

. In the rst case, it is possible to obtain a blank which is closed atthe rear, which has the advantage of being absolutely fluid-tight,wherevas in the second case, as the blank is open at both ends, it isnecessary tov t ends thereto by any 'method. On the other hand, the mainadvantage'obtained by the Ause of a tube is a considerable saving ofmaterial, which may be as much 4as 20 to 25%, as a result of thereduction of waste vin machining; furthermore, the rate of manufacturemay be much faster.

Although the useV of tubes is suitable in particular for the manufactureof hand-grenades and aerial bombs, it is quite the contrary when it isrequired to manufacture projectiles which are intended to be fired froma gun. As such projectiles are subjected, when firing, to the action' ofthe propelling gases, it is necessary for their case to be absolutelyfluid-tight at the rear; the slightest leak due to a hidden fault ofmanufacture might, -in fact, be suicient to cause serious accidents whenthey are being red. This is the reason why, in the manufacture ofartillery projectiles, it is preferred in general to renounce theadvantages that may be obtained bythe use of tubes and to adhere to theold method consisting in using a body manufactured from a bar andcompletely closed at the rear. v i

` As the casing of projectiles equipped with fins, vwhich are intendedto be fired by mortars, only have to support a moderate force when theshot is fired, it should be Amade as light as possible, and it would bea great advantage in this case to be able to manufacture it from atubular blank,

the only problem to be solved, which has not yet been solved in asatisfactory. manner, beingthat of the duid-tightness at the rear.

The present' invention is intended to fill this need.v -It'relates to' aprojectile equippedl with which is'provided with a' screwthreaded rearorifice,` into lwhich is screwed .a nipple which is secured, at any rateafter mounting.y to a tail supportingfthe iins, said projectile beingremarkable in particular in that the con- `nection between saidk tailand the body of the projectile isv provided .with ametalloplasticfdeformable fluid-tight joint mounted in an annularhousing provided inlthe bodygof zthezprojectile, `said Vjoint-'beingdeformedsby compression; imits housing by a circular shoulder of thenipple when arrangement' enables the sheath to become des "Thereistherefore Y. of its housing a sufficient pressure same is screwed intothe body of the projectile.

The fact that this fluid-tight joint is deformable by the action ofscrewing the nipple has the eiect that, after said nipple is'mounted,the joint completely fills its housing andthus makes the rear of theprojectile duid-tight. According to another characteristic of theinvention, the duid-tight joint is provided withv ai malleable metalsheath, which is open circularly on one side and contains a plasticmaterial.

formed'without crumpling and without its edges overlapping one anotherwhen the plastic mate- Yrial is compressed.

zjSince the time'takenby the projectile to trayel through the barrel ofa mortar'is very short,=the

joint is only slightly heated and may very well be made, internally, ofcardboard.

When the' jointis'compressed, itl first undergoesa considerabledeformation whichis permanent and irreversible, `owing to thecrushing'of the plastic material which has no natural rigid'- ity,` themetal sheath only offering a slight regsistance to this deformationowing to its annular shape which enables it to undergo largerdeformations by the action of small forces. i

' At the end of this period of compression, the

joint has assumed substantially the shape of its housing, save in thecorners of same, where there remains a small space of approximatelytriangular cross-section. f' -If the compression of the joint iscontinued, the pressure caused by the resistance to crushing offered bysaid'joint quickly increases and offers more and morev resistance tofurther deformations. As the plastic material is'thus solely incompression, it acquires a certain resilience.

during the rst period of the compression, plastic and permanentdeformation of theljoint by a slight pressure which slowly increases,whereas during the second period which is shorter, the jointisresiliently deformed, il. e. ,in a reversible manner, by a larger-force-Which quickly increases with thecompressionpath:A In order thatthe joint shall provide fluid-tightness it.is,necessary for it to exert`onA the walls to counterbalance. that of the gases, which is lonlypossiblek if saidV joint is in the'region of resilient deformations, i.e. the second part of the compression path.

Fluid-tightness will be kmore eicient. as the 3 fect so long as thescrewing travel of the nipple is only limited by the compression of thejoint.

The metal sheath is preferably given a rectangular cross-section withrounded corners, whereas its housing in the projectile is of purelyrectangular cross-section.

The joint is thus prevented, as it is deformed by the pressure of thescrew when the nipple is being tightened from being pinched andproducing a jamming which would make it impossible to screw the nippleright home; on the contrary, it only more completely lls the spaceprovided for its uid-tight functions. Furthermore, the presence of therounded corners of the sheath has the effect of providing smallexpansion spaces for the gases.

In a particular embodiment of the invention,v

the portion which forms a nipple and which is adapted to engage in therear orifice of the projectile body is provided with two groundcylinldrical bearing surfaces of diiferent diameters, which are axiallystepped and respectively engage in corresponding circular recessesprovided at the rear of said projectile body, the housing for thefluid-tight joint being formed by the recess of large diameter.

This makes it possible to obtain a perfectly guided sliding deviceWhich, at the end of its travel, locks the fluid-tight joint absolutelyaccurately in its housing. The length of the small diameter bearingsurface is such that the same begins to engage in its recess before theHuidtight joint begins to be compressed in its housing, whereby saidjoint is prevented from being driven back and jammed when the nipple isbeing screwed tight.

The use of these two ground bearing surfaces furthermore has theadvantage of eecting a suitable centring of the ns on the axis of theprojectile, which is very important for the accuracy of ring. The sameresult cannot be obtained when, as is generally the case, the tail isonly provided with a simple screw-threaded nipple adapted to screw in ablind hole bored in the end of the projectile.

For the purpose of breaking the jet of gases. by expansion, and ofpreventing it from propagating inside the joint, according to a furthercharacteristic of the invention, a circular expansion groove is providedon the periphery of the large diameter ground bearing surface.

The tail of the projectile may advantageously be manufactured ofpreferably untreated drawn steel tube, instead of using a tail' which ismachined from a bar; a saving of material and an economy of manufactureis obtained thereby. In this case, the coupling between the tail and thebody of the projectile comprises a separate part forming a connectionwhich is screwed right home in the projectile, ay second screw-threadprovided on said connection serves for screwing on to the tail. Thisconnecting member being of small size can be mass produced with thegreatest accuracy, which is an advantage when it comprises groundcylindrical portions, the accuracy of which is an important matter.

Additional fluid-tightness is given to the device .'by varnishing thewhole of the above described connection when mounting it. Finally, alayer of pitch cement may provide a final means for preventing the gasesfrom passing.

Other peculiarities of the projectile according to the invention willbecome apparent from the ensuing description.

In the accompanying drawing:

yafter compression and deformation of the fluidtight joint and the tailbeing screwed right home. Fig. is a general View, in axial section, of aprojectile equipped with ns according to the invention, provided with atail which has been machined from a bar with its nipple.

Fig. 6 shows,` in partial axial section, the detail of the fluid-tightcoupling, after screwing the tail (Fig. 5) on the projectile.

The projectile shown in Fig. 1 comprises a tapered body I and acartridge-holder tail 2 provided with fins 3; said tail is adapted toscrew on the rear of the projectile body I; in the example described, itis a perforated tail of known type, made from a drawn steel tube; anintermediate member or nipple 4, which is adapted to screw, on the onehand in the front part of said tail 2, and on the other hand in the rearpart of the projectile body I, acts as a connection between the tail andthe projectile body. It is obvious that as shown in Figs. 5 and 6, thetail could also be of any type, machined from a bar and having at theend thereof a screw-threaded nipple.

The body I of the projectile is made from a tube section. Consequentlyit has, after shrinking and machining the front and rear ogivalportions, a front orifice 5 and a rear orifice 6; said orice 6 is tappedat 'I so that the connection li, which forms a nipple, can be screwedtherein.

The tubular tail 2, for its part, is tapped at 8 'at its front part inorder to enable the connection 4 to be screwed.

A deformable joint 9 forms a seal for the propelling gases between theconnection 4 and the body I.

The projectile body I has, at -the rear part thereof, two steppedconcentric circular recesses: the large diameter recess I0 iscomparatively deep and serves as a housing for the sealing joint 9 (Fig.2); the inner recess II is shorter.

The connection 4 is screw-threaded at both Yends at 8' and 'I' so thatit can screw, on the one hand into the tail 2, and on the other handinto the rear orifice 6 of the body I which it completely closes; saidconnection is such that it can ber screwed right home in the body of theprojectile with a screwing torque which is calculated proportionally tothe capacity of deformation of the joint 9 and to the axial travel ofthe connection 4 when it is being screwed into the body I, and also tothe strength of the thread 'I' and the pressure of use and of reception.

The connection 4 is provided with two accurately machined cylindricalbearing surfaces I2 and I3, the respective diameters of whichcorrespond, with a very slight play, to the diameters of the tworecesses I 0 and II. Said bearing surfaces serve in the rst place forguiding and centring the connection 4, and consequently the tail 2 whenit is being mounted, which is very important in order that the finsshall be accurately in the axis.

The large diameter bearing surface l2 moves like a piston inside therecess II) which acts as a cylinder.

The small diameter bearing surface I3 penetrates inside the recess I Iand separates the fluidtight joint 9 from the screw-thread i and makesit possible to prevent said joint from jamming in the screw while it isbeing tightened, which might cause it to lock; it is long enough topenetrate into its housing I I before the joint 9 begins to becompressed (Fig. 2).

The housing of the fiuid-tight joint 9 is bounded, in the radialdirection,A by the inner face I4 (Fig. 3) of the recess I0 and by theperiphery I5 of the bearing surface I3, and in the axial direction, bythe end I0 of the recess I0 and by the annular face I1 between thebearing surfaces I2 and I3.

When the connection 4 is screwed into the rear orice 9 of the projectilebody I, the uidtight joint 9 is compressed more and more between theface I I and the end I6 of the recess I0 which serves as a housingtherefor, until the fluid-tight joint 9, which is deformed by thepressure, completely lls its housing, without leaving the slightestpossible leak (Fig. 4) The joint 9 being completely compressed, thereremains a certain empty space between the front part I3 of the bearingsurface I3 and the bottom I'I of the recess II.

The fluid-tight joint 9 shown in Fig. 3 comprises a deformable metalsheath which is circularly slit along one of its sides, at 2|; saidsheath contains a plastic material 22 such as cardboard. The existenceof the rounded corners of the sheath 20 eliminates any risk of saidsheath becoming pinched and jammed between the partitions of its housingwhile the tail is being screwed on, and little by little it assumes thefinal shape shown in Fig. 4 in which it completely fills its housing. Itthen only remains to screw the tail 2 on to the connection 4 until theface I8 comes into contact with the face I9 of the projectile; the tailthus acts as a lock-nut, and if the faces I8 and I9 have been carefullytrued, the tail is perfectly centred on the projectile.

A circular expansion groove 23 (Fig. 2) provided on the periphery of theground bearing surface I2 has the effect of breaking the jet of gaseswhen the shot is fired and breaks its propagation in the direction ofthe uid-tight joint 9. Said groove also has the advantage of decreasingthe bearing surface I2 which is thus easier to construct.

The connecting member 4 is covered with a coat of varnish not shown inthe drawing, and a mass of pitch cement 24 lodged in the end of the bodyI makes the rear part of the projectile still more fluid-tight.

In the embodiment shown in Figs. 5 and 6, the tail 2 and its nipple 25are in one piece, being assumed to have been machined from a bar.

The details of the fluid-tight joint, the bearing surfaces of the nippleand their housings in the body of the projectile are the same as in theexample of Figs. 1 to 4.

The only dierence consists in the fact that, instead of rst screwinghome the connection in the projectile, in order to press the fluid-tightjoint in its housing, the joint is compressed by means of the tailitself. The construction is simpler, but the mounting and the centringof the tail are not so accurate, since said tail can only be screweduntil the joint 9 is completely compressed in its housing; a slight playmust therefore remain between the faces I8 and I9, and the tail cannotact as a lock-nut in the manner described in the example of Figs. 1 to4.

It is obvious thatl the invention has only been illustrated anddescribed by way of example and that, without exceeding its scope, manyother embodiments could be constructed.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. In a projectile equipped with ns, a hollow body provided at the rearwith a tapped orifice followed in the outward direction and axially bya. rst cylindrical recess, then by a second rear one of larger diameterand connected at right angles to the former by a flat surfaceperpendicular to the longitudinal axis of said body, a nipple screwed insaid tapped orifice and provided with two ground cylindrical bearingsurfaces of different diameters, corresponding to the diameters of saidrecesses, said surfaces being axially stepped, connected by a iiatsurface perpendicular to the longitudinal axis of said nipple andrespectively engaged in said recesses and the bearing surface engaged inthe first cylindrical recess having an axial length greater than that ofsaid recess so that an annular space of rectangular longitudinal radialsection is left in said second rear recess by said nipple, a deformablemetallo-plastic fluid-tight annular seal located in said annular spaceand compressed by said nipple between said flat surfaces, and a tailprovided with ns and connected to said hollow body by means of saidnipple.

2. A projectile equipped with ns according to claim 1, wherein thelength of the small diameter bearing surface of said nipple is such thatsaid bearing surface is already engaged in the corresponding recess ofsaid hollow body before said fluid-tight joint begins to be compressedby said nipple.

3. A projectile equipped with fins according to claim 1, wherein acircular expansion groove is provided on the periphery of the largediameter ground bearing surface of said nipple.

4. A projectile equipped with ns according to claim 1, wherein saidmetallo-plastic annular seal comprises a malleable metal sheath,provided with a circular slit and having a longitudinal radialcross-section in the form of a horseshoe, the longitudinal axis of whichis parallel to the longitudinal axis of said body, and a plasticmaterial in contact with the flat surface of the rear recess of saidbody through said circular slit.

JOSEPH RAYMOND JASSE.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 737,964 Roach Sept. 1, 19031,313,926 Stokes Aug. 26, 1919 1,872,107 Bond Aug. 16, 1932 2,083,658Napier June 15, 1937 2,315,145 Wauters Mar. 30, 1943 2,362,534 BrandtNov. 14, 1944 FOREIGN PATENTS Number Country Date 711,463 France June30, 1931

